Some Results On Quasi-thin Scheme

In this thesis,we study the schurity and separability problem of a certain type of scheme called the quasi-thin scheme.The main results are:· Let X =(?,S)be a Quasi-thin scheme.If X has only one orthogonal and this orthogonal is thin,then any point extension of X? is 1-regular if and only if the action of S1 on S2 by right multiplication is transitive.in this case,|S2|?|S1|/2.· Let T ??u,v,w} be a non-exceptional triangle of a quasi-thin scheme X =(?,S).Then there exist relations a?u*w and b?w*v for which |ab?u*v|=1.· Given a quasi-thin scheme X ?(?,S);???.If X contains exactly one orthognal u,and u is thick,then:X?X?S1(?)X?T,(?)???.· Any commutative klein scheme is schurian.